1. Field of the Invention
The present invention relates generally to mechanisms for cooling heat producing components on electronic circuit boards, and more particularly, to the cooling of components by air flow generated by fans.
2. Description of the Related Art
Instruments for collecting data or information from an environment or unit under test may be coupled to and controlled by computer systems. Data collected by these instruments may be used to control units being tested (e.g., an overheated unit may be shutdown) or an environment (e.g., ventilation systems may be activated if a certain chemical is detected in the air). Data may also be displayed to a user for control and/or experimental purposes (e.g., to improve the design of the unit being tested). Instruments and/or computer systems may also perform various data analysis and data processing on acquired data prior to control of the unit and/or display of the data to the user. Examples of various types of instruments include oscilloscopes, digital multimeters, pressure sensors, etc., and the types of information that might be collected by respective instruments include voltage, resistance, distance, velocity, pressure, oscillation frequency, humidity or temperature, among others.
Instrumentation systems such as those described above may run on a platform such as PXI (Peripheral Component Interconnect (PCI) extensions for Instrumentation). PXI may combine a high-speed PCI bus with integrated timing and triggering features designed for measurement and automation applications to deliver performance improvements over other architectures. PXI may be built on a modular and scalable CompactPCI specification and the high-speed PCI bus architecture. As a result, PXI products may maintain interoperability with CompactPCI, offering increased mechanical integrity, easier systems integration, and more expansion slots than desktop computers. However, due to the compact design of these modules, parts of the module may be difficult to cool sufficiently.
FIG. 1A illustrates an exemplary chassis 100, e.g., a chassis conforming to any one of the following standards: VXI (Virtual Machine Environment (VME) extensions for Instrumentation), VME, CompactPCI, CompactPCI-Express, PXI, or PXI-Express. The chassis 100 includes a housing that is configured to define a plurality of slots. Each of exemplary plug-in modules 102A-C may be inserted into the plurality of slots of chassis 100.
FIG. 1B illustrates an internal structure of the exemplary chassis 100 showing plug-in module 102B inserted into the chassis 100. The plug-in module 102B may be guided during insertion into the chassis 100 by at least guide rails 104A-B until connectors 106 make connection. Connectors 106 may comprise a pair of connectors (not shown in FIG. 1B), one mounted on the plug-in module 102B and a mating connector mounted on the backplane 110. Additional circuitry 112 may be mounted behind the backplane 110 and may interact with the plug-in module 102B through the connectors 106. Backplane 110 and guide rails 104A-B may be coupled or attached to sub-rack support members 116 and 117. Pusher fan 114 may force air into the chassis 100 and under the support member 116 (arrows indicate typical air flow). Air flowing under the support member 116 may be redirected by vanes 118A and 118B and deflector 120 toward heat producing components of plug-in module 102B.
It is desirable to mount additional heat producing components on the front of the backplane 110 (such as: electronic switches and/or bridges). However, the air flow depicted in FIG. 1B may be ineffective in providing sufficient cooling to heat producing components mounted on the front of backplane 110 or mounted near the connector end of plug-in module 102B. Air flow eddies swirling in the region of components mounted on the backplane 110 trap the additional heat produced by these components and generate an elevated ambient air temperature in the air surrounding the components. The resulting excessive component temperatures may result in shorter component lives and/or unexpected failures.